Samuel, it looks like that drip pan bracket under the cook box is in need of some tightening and straightening out. Good luck on the conversion.
If those SS bolts are for the "dropsies" fix, they may not work too well. They are not self tapping and will be tough to get to bite into the metal. Plus, you would probably want to use a "slightly" smaller drill bit as the 1/4" bit might make the hole too lose for the bolts to have anything to grab on to. Rather than finding SS self tapping bolts, you could use what you have and simply tap the holes with a machinist tap. You can get them online (amazon) or probably at most HW stores, like HD, ACE, Menards, etc. Sometimes they come with the correct size drill bit for the tap as well as it needs to be slightly smaller than the bolt size. Just like if using a self tapping bolt.
Do you have access to a welder or know someone that does? It would be a lot easier to simply weld them on.